Present hearing aid microphones are typically limited to being optimized for directional sensitivity or omnidirectional sensitivity to sounds that impinge upon the diaphragm of the microphone. The directivity of a microphone is the sensitivity of a microphone to a sound component at different angles of incidence. The microphone is typically optimized to be more sensitive to one component of the sound over the other. However, undesirable noise may occur within the hearing aid when a microphone that is optimized for a given directional component of an impinging sound receives higher levels of sound having other directional components.
Typical hearing aids either include a non-directional or directional hearing aid microphone system. An omnidirectional hearing aid system allows the user to pickup sounds from any direction. When a hearing aid user is trying to carry on a conversation within a crowded room, an omnidirectional hearing aid system does not allow the user to easily differentiate between the voice of the person the user is talking to and background or crowd noise. A directional hearing aid helps the user to hear the voice of the person they are having a conversation with, while reducing the miscellaneous crowd noise present within the room.
A hearing aid that provides selectivity between a directional and an omnidirectional mode will experience a change in sensitivity that is readily apparent when switching between modes. This change in sensitivity can be very uncomfortable to the hearing aid user.
Controllable directivity and sensitivity can help a wearer of a hearing aid to better understand a person speaking directly at the wearer while reducing the level of undesirable noise. Thus, there is a need for a hearing aid device having a microphone that can be acoustically optimized for both directional and omnidirectional sensitivity, depending upon the circumstances presented to the wearer of the hearing aid.